Alabama Chief Justice Roy Moore on Thursday warned that allowing gay couples to marry will lead to the legalization of incestuous or plural marriages.

A federal judge in two separate cases has declared Alabama's ban on gay marriage unconstitutional. Unless a higher court interferes, Alabama will become the 37th state, plus the District of Columbia, where gay couples can marry on Monday, February 9.

Moore called on Governor Robert Bentley and judges to defy the ruling.

In comments with the media, Moore declared “we will have a confrontation” if the order is enforced.

Moore said that speaking out was his duty because directing state officials how to act is his job.

He told that he agreed with California Supreme Court Justice Marvin Baxter's dissent in the 2008 case that declared California's ban unconstitutional.

“Who can say that, in 10, 15 or 20 years, an activist court might not rely on the majority's analysis to conclude, on the basis of a perceived evolution in community values, that the laws prohibiting polygamous and incestuous marriages were no longer constitutionally justified?” Baxter wrote.

“I've said the very same thing. Incest is next. Or polygamy,” Moore said.

(Related: Ethics complaint filed against AL judge Roy Moore over call to ignore gay marriage ruling.)